The invention relates to open-end spinning machines, and more particularly to arrangements for stopping the advance of spun yarn through the outlet portion of the machine in response to a yarn breakage condition.
In the yarn-withdrawal portions of known open-end spinning machines, a pair of reversible draw-off rollers are disposed downstream of the spinning chamber for withdrawing spun yarn through a withdrawal tube at the output end of the chamber. The yarn advanced by the rollers enter distributing grooves on a traversing distributing cylinder, which is in frictional driving contact with a take-up bobbin. The rotation and traversing movement of the cylinder is effective to lay the spun yarn in a roving pattern on the periphery of the bobbin to define a yarn package. The drive for the cylinder, like that of the rollers, is made reversible, so that upon a suitable command associated, e.g., with a yarn breakage condition, the rollers and cylinder may be reversed to establish a conventional "spinning-in" condition whereby the yarn can be withdrawn into the spinning chamber through the withdrawal tube.
In such known systems, a finite interval is necessary between the detection of a yarn breakage condition and the initiation of a pre-set program for the application of reversing signals to the draw-off rollers and the distributing cylinders to start the spinning-in mode. During this finite interval, it is necessary to bring the yarn advance to a stop, to make sure that the broken yarn end does not exit from the distributing cylinder. Up to now, the stopping of advance of the yarn following a detection of a yarn breakage condition has required the connection of a mechanical brake to the drives for the draw-off rollers and distributing cylinders. The necessity of providing such additional components has proved to be a space-consuming and costly expedient.